1. Field of the Invention
The invention relates to the field of superconducting radiofrequency (srf) window assemblies for transmitting radiofrequency (rf) power from external sources to cavities such as those within an electron beam accelerator.
2. Description of the Related Art
A large number of microwave devices require a vacuum environment in order to operate. Radiofrequency electron beam accelerator cavities, klystrons and magnetrons are a few examples of such devices. It is necessary to introduce or extract microwave energy into or out of these devices between the atmosphere or partial vacuum and a vacuum or higher vacuum. This is commonly accomplished using a component which is transparent to microwave power but functions as a barrier to atmospheric air, dust and debris. These components are generally referred to as "radiofrequency (rf) windows."
Particulate matter adversely affects the performance of electron beam accelerator cavities. Consequently, it is desirable to assemble the cavities entirely within an ultra clean room to minimize the exposure of the cavities to particulates. This procedure requires the direct attachment of an rf window to the cavity, which in turn, imposes certain requirements on the rf windows. The rf window must function as an ultra high vacuum component, i.e., be hermetically sealed and withstand a pressure differential of three (3) atmospheres; operate under cryogenic conditions (2.degree. K) and withstand thermal cycling from 2.degree. K to 300.degree. K; minimize radiofrequency power loss; and transmit a broad band of radiofrequencies. The window may be used as an intermediate window between a cryogenic ultrahigh vacuum and a lesser vacuum that has another window between the atmosphere and the lesser vacuum. Existing rf windows do not adequately possess these features.